1. Field Of The Invention
The present invention relates to a low tire pressure warning device and, more particularly, to a low tire pressure warning device having a bladder and piston arrangement which causes the release or "streaming" of a compacted, colored streamer in response to a decrease in tire pressure below a predetermined level.
It is useful in the maintenance of vehicular tires, and particularly multi-axled truck trailers and tankers, to have early warning of a drop in tire pressure. This both prevents unnecessary wear of the tires and aids in the safety of operation. Thus, the present invention is directed to a convenient, relatively inexpensive and effective device to achieve early warning of tire pressure drop.
2. Prior Art Statement
U.S. Pat. No. 4,310,014 describes a pressure signaling system which involves the use of a spring-loaded set of indicators which rises to show a particular indicator when the tire pressure falls below a predetermined level. The indicators are color bands on a tubular portion which operates as an integral part of the valve stem.
U.S. Pat. No. 4,262,529 describes a pressure sensitive indicating device which includes a visual indication of a predetermined pressure threshold level. The device contains a bladder designed to expand upon exposure to increasing pressure levels. Distention of the bladder displaces an element which causes visible color portions to be displaced with different color portions to indicate pressure change.
U.S. Pat. No. 4,244,214 illustrates a three color band visual tire pressure indicator which operates on a spring-biased rod which is precalibrated to the desired normal pressure.
U.S. Pat. No. 4,066,033 combines the spring biased piston tire pressure indicator with a preset air actuated whistle which responds to a predetermined threshold tire pressure and activates an electronic device which signals the vehicle operator (note that this is the first device described which alerts a driver to tire pressure problems without the need for him to be very close to the problem tire).
U.S. Pat. No. 4,024,829 teaches an air leakage warning device which utilizes the spring-biased piston and the concept of a rupturable rubber sack which ruptures at a predetermined pressure to give an audible signal.
U.S. Pat. No. 3,990,467 illustrates a combined tire valve stem and pressure guage which relies upon color bands to indicate whether tire pressure is above, at, or below the desired pressure.
U.S. Pat. No. 3,738,308 describes an alarm system which utilizes the spring-biased piston in conjunction with a signaling whistle detected by a sensing system on the vehicle which in turn generates a signal to the driver.
U.S. Pat. No. 3,230,968 relies upon pressure sensitive mechanisms with various color bands to indicate tire pressure.
Notwithstanding the foregoing prior art there is no teaching or suggestion involving the use of highly visible, colored streamers. The above prior art warning devices require either that the driver get out of his truck and walk all the way back and around the truck to check all tires or that complicated sound-responsive electronic singalling devices be incorporated into the devices for signalling the driver while still in the cab. Only the present invention enables a driver to look back from the front area of his truck and see the warning streamers when tire pressures are down. Only the present invention permits remote signalling without complicated and expensive electronic gadgetry. Only the present invention streamers alert passing cars to low tire pressure problems on trucks, and enable the drivers of the cars to give, e.g., a three beep, signal to the truck driver to warn him to inspect. Thus, only the present invention offers a low tire pressure warning system which combines the advantages of low cost, non-electronic, remote signalling and third party alert signalling. For these reasons, the present invention is neither taught nor rendered obvious by the prior art.